We continued and expanded recording of non-electrical signs of excitation processes in the nervous system. We found that the turbidity of the dorsal column of the frog spinal cord increases in response to electric stimuli applied to the dorsal roots. We obtained records showing a rise of the temperature of the cord evoked by afferent impulses. Next, we demonstrated that the dendrites of the amacrine and ganglion cells in the frog retina respond to light stimuli with slow contractions. Finally, we analyzed the sequence of light-induced events in the retina by taking heat production as an index. Attempts are now being made to elucidate the nature of these newly discovered mechanical and thermal phenomena in the nervous system.